Issue: REMF-DESTRUCTION-UNSPECIFIED (Version 5)

[David A. Moon <Moon@STONY-BROOK.SCRC.Symbolics.COM>]

I don't have the mail message you referred to ("I suggest that the text
Amemdment I from my 14 February mail be used verbatim as the proposal.").
However, I like the way you dealt with NCONC in version 5, I don't
see any need for a separate proposal.

Generally this looks okay.  I thought you were going to remove this:

 (NSUBSTITUTE new-object old-object sequence ...)
 (NSUBSTITUTE-IF new-object test sequence ...)
  when sequence is a list, is permitted to SETF any part, CAR or
   CDR, of the top-level list structure in that sequence.
  when sequence is an array is permitted to SETF the contents of
   any cell in that array which must be replaced by NEW-OBJECT.

since in fact there is no need to give NSUBSTITUTE the freedom
to modify anything more than what it is required to modify.  I
still think it should be removed, just as NSUBST was removed.